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During the process of one‐dimensional consolidation with a threshold gradient, the seepage front moves downward gradually, and the problem is indicated as a Stefan problem. The novel feature in this Stefan problem is a latent heat that varies inversely with the rate of the moving boundary. An exact solution for the external load that increases in proportion to the square root of time is constructed using the similarity transformation technique. Computational examples concerning the effect of different parameters on the motion of the seepage front are presented. The exact solution provides a worthwhile benchmark for verifying the accuracy of numerical and approximate methods. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Stochastic delineation of wellhead protection area in fractured aquifers and parametric sensitivity study 总被引:1,自引:0,他引:1
S. Chevalier M. A. Buès J. Tournebize O. Banton 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(3):205-227
In many countries, the setup of protection areas around every drinking water well was instituted at a national level in order
to preserve the quality of water as well as the perennially of the resource. Wellhead protection surfaces have been defined
using capture zones showing the area influenced by a well within a certain time. A stochastic method is developed for delineating
time-related capture zones in fractured aquifers characterised by a low porosity and a high degree of fracturing. The flow
velocity within the fractures is determined statistically depending on the distribution of the fracture features and the mass
transfer solution is obtained through a particle tracking algorithm. Probabilistic capture zone curves are obtained as a function
of the travel time of particles to the well and the percentage of particles apt to be extracted up to this time. A sensitivity
study of fracture network parameters leads to the conclusion that orientations and aperture distribution of the fracture sets
are of primary importance to the wellhead protection delineation. 相似文献
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云南铜矿是历史上开发最早的地区之一,至今已知的大-中型矿区(除边远的羊拉、托顶之外),历史上几乎都不同程度地被开采过。也有历史上曾采冶辉煌,但至今却没有铜矿产出,找铜工作者也不知道的“古老铜矿”,俞元(澄江)铜矿即是一例。研究、考证采铜史料,认为澄江铜矿、东川茂麓厂、寻甸铜矿、永平宁台厂等,应列为新世纪重新评价的找铜目标。 相似文献
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测绘标准管理信息系统是标准信息化建设的主要内容,是测绘标准信息管理、应用及服务的重要基础支撑平台。本文结合开展测绘标准管理信息系统研究和建立的实际经验,根据标准信息建设与服务的技术现状和发展趋势,从设计要求、系统功能框架、标准信息管理、标准化工作管理、安全性和数据备份等方面介绍了测绘标准管理信息系统的设计思路,并就其实现方法和所采用的相应技术作了简单的叙述。 相似文献
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De-Fu Bu Feng Yuan Fu-Guo Xie 《Monthly notices of the Royal Astronomical Society》2009,392(1):325-331
Observations and numerical magnetohydrodynamic (MHD) simulations indicate the existence of outflows and ordered large-scale magnetic fields in the inner region of hot accretion flows. In this paper, we present the self-similar solutions for advection-dominated accretion flows (ADAFs) with outflows and ordered magnetic fields. Stimulated by numerical simulations, we assume that the magnetic field has a strong toroidal component and a vertical component in addition to a stochastic component. We obtain the self-similar solutions to the equations describing the magnetized ADAFs, taking into account the dynamical effects of the outflow. We compare the results with the canonical ADAFs and find that the dynamical properties of ADAFs such as radial velocity, angular velocity and temperature can be significantly changed in the presence of ordered magnetic fields and outflows. The stronger the magnetic field is, the lower the temperature of the accretion flow will be and the faster the flow rotates. The relevance to observations is briefly discussed. 相似文献